simple calculator for column fixture test

quotient

with exception test

public function quotient() {
if( $this->number2 == 0 ) {
throw new Exception( 'division by zero' );
}
return $this->number1 / $this->number2;
}

sum

public function sum() {
return $this->number1 + $this->number2;
}

sub

public function sub() {
return $this->number1 - $this->number2;
}